Row markers for agricultural implements, such as planters or the like, are utilized to float on the contour of the ground and provide a continuous visible marking that aids the operator in guiding the implement during successive rounds through the field. Since the outermost end of these markers is typically a considerable distance from the operator of the agricultural implement, it is not uncommon that such markers, from time to time, hit fences, small trees, or other obstacles found in fields, thereby damaging either the marker itself and/or such obstacles. Consequently, breakaway assemblies have been devised for such markers for permitting the marker to rotate about the vertical axis, away from the obstacle, but still remaining attached to the implement and in an undamaged condition.
A common problem with this type of apparatus is commonly referred to as "nuisance" failures. These typically occur due to fatique on the breakaway bolt, or some other weakness in the breakaway assembly. Since nearly every planter having markers thereon is equipped with breakaway protection, the down time associated with such "nuisance" failures can be extremely significant.
Prior art breakaway systems have typically provided a marker system which has the marker pivotally attached along a vertical axis to the frame of the implement and a shear pin is provided forwardly of such vertical pivot point for preventing such rotation unless the force from hitting an obstruction is so great as to break the shear pin holding it from such rotation. The prior art shear pins or bolts for preventing such rotation have heretofore been disposed in such a manner that they are sheared off when an obstruction is encountered by the marker. The problem with using a shear pin is that cyclic bending will continually occur during working conditions of the marker and this cyclic bending contributes to premature failure of the shear pin, thereby causing the aforementioned "nuisance" failures.
Consequently, there is a need for breakaway protection for markers which prevents cyclic bending of the pin or bolt, thereby reducing breakaways or "nuisance" failures as much as possible.